If you are feeling depressed, it could be the effect of "twisted thinking". There are many different twisted ways of thinking, but here I want to talk about two, overgeneralisation and the mental filter.If you can catch yourself making these errors, you can use strategies to overcome and dramatically improve your depression.
The first error, overgeneralisation is when you make the assumption that if something happens once, it will always happen for ever after.
You go for a job and don't get it. Overgeneralisation makes you conclude "I'll never get any job. It's completely hopeless". Overgeneralisation multiplies the pain of setbacks or rejections many many times. You could look at a setback as just an isolated event, but instead you interpret it as a message from the universe that all your endeavours are doomed.
Overgeneralistion can happen in spite of all the evidence. David Burns, in his book Feeling Good, tells about the depressed salesman who noticed bird dung on his car window and thought "That's just my luck. The birds are always crapping on my window!". When asked he could not think of another time in the last twenty years when this had happened. By becoming aware of when you are overgeneralising, and challenging it (for instance by asking whether it is true that something "always" or "never" happens) you can begin to overcome it.
The other form of twisted thinking that I want to discuss here is the mental filter. This happens when you focus all your attention on a small number of negative elements, giving them importance out of all proportion. For instance, if a student takes a test with 100 questions and gets ten of them wrong, the mental filter would make him obsess about those ten errors, ignoring the fact that he in fact scored 90%, an excellent mark. As another example, I might see thirty patients in a week and have one session that did not go well, which the patient did not think was helpful. The mental filter would make me concentrate on this, ignoring the fact that most of the other sessions that week, and most of the sessions with that patient in other weeks, did in fact go well. This sort of behaviour arises from depression. When we are depressed we can only respond to negative information,and that negative information makes us more depressed. We can learn how to recognise when the mental filter is operating and how to defeat it, saving ourselves much needless suffering.